1. Field of the Invention
The invention relates to new silanes or siloxanes, which have cyclic hydrocarbon radicals with fluorine or fluorohydrocarbon radicals, as well as to their synthesis and use for modifying the surface of solids, especially of finely divided silica.
2. Description of the Prior Art
Silanes or siloxanes which carry fluorine or fluorohydrocarbon radicals, endow the substrates on which they are applied, with water-repellent, oil-repellent, and possibly soil-repellent properties. The compounds are therefore used with success to modify the properties of inorganic or organic materials. Examples of such materials are building materials, such as, plaster, cement, mortar or shaped building materials, such as, tiles of clay or other porous materials, plaster boards, and prefabricated concrete components.
A further application of fluorine-containing silanes or siloxanes is in the modification of pigments and fillers, the modified form of which has improved compatibility with various organic media. This is shown, for example, in the greater ease of incorporating pigments into vehicles and in the reduced tendency of such pigments to separate and deposit. A modified, finely divided silica, especially one that has been pyrogenically produced, improves the suspension behavior of pigments, changes the thixotropy and decreases the evolution of gas from zinc dust paints.
Further possible applications are in the paper industry in which the products can be applied to the paper pulp in the manufacture of the paper, as well as to the already consolidated, still moist paper web or the finished paper. Fluoroorganosilicon compounds are furthermore suitable for treating textile materials, which may be present in the form of fibers or yarns, as woven or knitted materials, or in the form of a nonwoven fabric.
The synthesis of these compounds, however, creates difficulties. The preferred starting materials for synthesizing siloxanes with fluorinated hydrocarbon radicals by methods of the state of the art are silanes, which carry these fluorohydrocarbon radicals. The reason for this lies in the fact that the addition of fluoroalkylolefins to the SiH groups of silanes is facilitated by the presence of halogen atoms that are linked to the same silicon atom. However, the synthesis of siloxanes of the given structure from silanes with fluorinated hydrocarbon groups also creates difficulties, since these silanes, when hydrolyzed and condensed, preferably form cyclic siloxanes.
If, however, fluorinated hydrocarbons with olefinic double bonds are to be added to the SiH group of hydrogen siloxanes, it can be observed that this addition reaction is considerably more difficult, if there are other hydrocarbon or siloxy group substituents on the silicon atom.
The task of introducing fluorinated hydrocarbon radicals in a simple manner in siloxanes of a given structure in order to obtain compounds whose properties can be adjusted by the structure of the siloxane and by the special properties of the fluorinated hydrocarbon groups to meet the requirements of a particular application, has not yet been accomplished satisfactorily by the methods known to the art.